ADL5961ACCZ-R2 datasheet(27/34 Pages) AD

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Data Sheet

ADL5961

APPLICATIONS INFORMATION

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Rev. 0 | 27 of 34

Figure 68. SPI Chip Select Interface

SDIO Interface

The ADL5961 implements a 3-wire SPI that uses a single line for

transmission and reception of data. When receiving data, that is,

during a write operation to the ADL5961, the transmitter output

becomes high-impedance such that the transmitting device can pull

the data line low or high as desired. To connect this interface to

an SPI controller using a 4-wire interface, with separate data input

and data output lines, a series current-limiting resistor, as is shown

in Figure 70, is recommended to isolate the controller and target

outputs. This resistor provides protection in the event that both

outputs become simultaneously active.

Figure 69. Simplified SDIO Interface

Figure 70. SPI 4-Wire to 3-Wire Interfacing

TEMP Interface

In addition to the on-chip digital thermometer, the TEMP pin can be

used to monitor the die temperature by applying a known reference

current into the TEMP pin and measure the pin voltage relative to

ground. An injected current of 42 µA results in a nominal voltage of

0.775 V at 25°C and a temperature slope of approximately −1.54

mV/°C.

Figure 71. Temperature Diode Interface

LO INTERFACE CONFIGURATION

The LO interface supports a bypass mode, three different multiply

modes, and one divide mode that are selectable through Register

0x20 in the SPI. Each of these operating modes is discussed in the

Bypass Mode (BYPASS = 1) section through the Multiply by 4 Mode

(LOMODE = 3) section.

Bypass Mode (BYPASS = 1)

The LO signal is routed directly to the internal downconversion

mixers, bypassing the frequency multipliers and dividers. The LO

multipliers and dividers and the offset frequency interface are disa-

bled. The ADL5961 achieves the widest bandwidth and the highest

dynamic range in this mode.

Divide by 2 Mode (LOMODE = 0)

The frequency of the LO input signal is divided by two before

being passed through the offset mixer and supplied to the down-

conversion mixers. If supported by the frequency range of the RF

signal, this LO operating mode provides a means to extend the

VNA measurements frequency range to less than the minimum

frequency supported by the LO source itself. This operating mode

can be used either with the offset frequency interface enabled or

disabled.

Multiply by 1 Mode (LOMODE = 1)

The LO signal bypasses the LO multipliers and dividers but is

routed through the offset mixer to the downconversion mixers.

The intended use is with the offset frequency interface enabled.

Although it can be used with the offset frequency interface disabled,

improved performance is achieved by selecting the bypass mode

(BYPASS = 1) instead.

ADL5961ACCZ-R2 数据表(PDF) 27 Page - Analog Devices

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